JP2021093246A - Lighting device and luminaire - Google Patents

Abstract

To obtain a lighting device and a luminaire, capable of achieving an easy control in the present invention.SOLUTION: A lighting device according to the present invention, comprises: a power supply circuit; a series circuit having a light source connection part for connecting a light source and a switching element connected to the power source connection part in serial and in which an output voltage of the power supply circuit is supplied to both ends; and a control part that turns on/off the switching element to control a light source current flowing in the light source. The control part maintains the output voltage to a fixed value irrespective of a voltage of both ends of the switching element after the output voltage is set to the fixed value so that the voltage of both ends of the switching element is matched to a predetermined first voltage.SELECTED DRAWING: Figure 2

Description

The present invention relates to a lighting device and a lighting device.

Patent Document 1 discloses an illumination lighting device that drives a solid-state light emitting element by supplying power from a DC power source. This illumination lighting device includes a voltage conversion circuit, a constant current lighting circuit, a voltage detecting means, and a control means. The voltage conversion circuit converts the DC power supply voltage supplied from the DC power supply into a voltage to change the output voltage. The constant current lighting circuit has a transistor that is connected in series to the solid-state light emitting element to form a series circuit. The constant current lighting circuit applies the output voltage of the voltage conversion circuit to the series circuit to keep the drive current flowing through the solid-state light emitting element constant.

The voltage detecting means detects the voltage across the transistor. The control means controls the voltage conversion circuit so that the detection voltage of the voltage detection means becomes a preset set voltage while the drive current is kept constant by the constant current lighting circuit, and the output voltage of the voltage conversion circuit. Is variable.

Further, the lighting device includes a secondary battery, a charging circuit for charging the secondary battery, and an emergency power supply circuit. The emergency power supply circuit converts the DC voltage from the secondary battery into a voltage to change the output voltage in an emergency. The secondary battery, the charging circuit, and the emergency power supply circuit are provided between the output side of the voltage conversion circuit and the solid-state light emitting element. Further, the lighting device includes a lower limit value setting means for setting a lower limit value of the output voltage of the voltage conversion circuit.

According to the configuration of Patent Document 1, even if the characteristics of the solid-state light emitting element vary, the output voltage of the voltage conversion circuit can be adjusted according to the characteristics of the solid-state light emitting element. Therefore, the loss of the transistor of the constant current lighting circuit can be suppressed. In addition, the charging current of the secondary battery can be secured.

Japanese Patent No. 5297119

However, in Patent Document 1, a constant current is realized while controlling the output voltage of the voltage conversion circuit. Therefore, control may be complicated.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to obtain a lighting device and a lighting device capable of realizing easy control.

The lighting device according to the present invention has a power supply circuit, a light source connection portion for connecting a light source, and a switching element connected in series with the light source connection portion, and the output voltage of the power supply circuit is connected to both ends. A series circuit to be supplied and a control unit that turns the switching element on and off to control the light source current flowing through the light source are provided, and the control unit has a first voltage in which the voltage across the switching element is predetermined. After setting the output voltage to a fixed value so as to match, the output voltage is maintained at the fixed value regardless of the voltage across the switching element.

The lighting device according to the present invention includes a power supply circuit, a plurality of series circuits, and a control unit, and each of the plurality of series circuits includes a light source connection unit for connecting a light source and the light source connection unit. It has a switching element connected in series, and the output voltage of the power supply circuit is supplied to both ends, and the control unit turns the switching element on and off for each of the plurality of series circuits and flows through the light source. After controlling the current and setting the output voltage to a fixed value so that the voltage across the switching element having the smallest voltage across the plurality of switching elements of the plurality of series circuits matches the predetermined first voltage. The output voltage is maintained at the fixed value regardless of the voltage across the plurality of switching elements.

The lighting device according to the present invention includes a power supply circuit, a plurality of series circuits, and a control unit, and each of the plurality of series circuits includes a light source connection unit for connecting a light source and the light source connection unit. It has a switching element connected in series, and the output voltage of the power supply circuit is supplied to both ends, and the control unit turns the switching element on and off for each of the plurality of series circuits and flows through the light source. After controlling the current and setting the output voltage to a fixed value so that the average value of the voltages across the plurality of switching elements of the plurality of series circuits matches a predetermined first voltage, the voltage across the series is not affected. The output voltage is maintained at the fixed value.

In the lighting device according to the present invention, after setting the output voltage of the power supply circuit to a fixed value, the output voltage of the power supply circuit is maintained at a fixed value. Therefore, easy control can be realized.

It is a circuit block diagram of the emergency lighting device which concerns on Embodiment 1. FIG. It is a circuit block diagram of the lighting circuit which concerns on Embodiment 1. FIG. It is a figure explaining the short circuit waveform which concerns on Embodiment 2. FIG. It is a figure explaining the short circuit waveform which concerns on a comparative example.

The lighting device and the lighting device according to the embodiment of the present invention will be described with reference to the drawings. The same or corresponding components may be designated by the same reference numerals and the description may be omitted.

Embodiment 1.
FIG. 1 is a circuit block diagram of the emergency lighting device 100 according to the first embodiment. The emergency lighting device 100 is, for example, an guide light. The emergency lighting device 100 is held and installed in the fixture body. The emergency lighting device 100 includes light source units 41 and 46 and a lighting device. The lighting device includes a unit 10 and a battery 250.

The light source units 41 and 46 have a light source for ensuring brightness in an emergency and in regular use. The light source is, for example, an LED. As a result, the energy consumption of the emergency lighting device 100 can be suppressed. The unit 10 receives power from the external power source AC and charges the battery 250. The external power supply AC is an AC power supply or a commercial power supply. The battery 250 supplies power to the light sources 41 and 46 in an emergency. The battery 250 is, for example, a secondary battery.

The unit 10 includes an input filter circuit 1, a regular power supply circuit 2, a charging circuit 3, a lighting circuit 4, an emergency lighting circuit 5, a power generation generation circuit 6, and a control circuit 7. The control circuit 7 includes a control unit 50. The control unit 50 is, for example, a microcomputer.

The input filter circuit 1 includes a fuse 11 for protecting overcurrent, a capacitor 12 for alternating current, and a diode bridge 13 for converting alternating current into direct current. One end of the fuse 11 is connected to the high potential side of the external power supply AC. The other end of the fuse 11 is connected to the positive electrode of the capacitor 12 and the high potential side of the input of the diode bridge 13. The negative electrode of the capacitor 12 is connected to the low potential side of the external power supply AC and the low potential side of the input of the diode bridge 13. The output of the diode bridge 13 is connected to the regular power supply circuit 2. The low potential side of the output of the diode bridge 13 is connected to the grounding terminal.

The input filter circuit 1 includes a turn-off signal detection circuit 14 that detects a turn-off signal, and a photocoupler 15 that transmits the turn-off signal to the control unit 50. Further, the switch SW turns on / off the power supply from the external power supply AC to the emergency lighting device 100. The off-off signal detection circuit 14 may detect the on / off of the switch SW.

The regular power supply circuit 2 is composed of an insulated flyback circuit. The normal power supply circuit 2 is supplied with electric power from the external power supply AC during normal use to charge the battery 250. Further, the normal power supply circuit 2 lights the light source units 41 and 46 during normal use. The control unit 50 controls the regular power supply circuit 2. Here, the term "civil time" indicates a normal state in which the external power supply AC is not in a power failure state or a pseudo power failure state.

In the regular power supply circuit 2, the capacitor 201 is connected in parallel with the output of the diode bridge 13. The positive electrode of the capacitor 202, one end of the resistor 203, and one end of the primary side of the transformer 220 are connected to the positive electrode of the capacitor 201. The cathode of the diode 204 is connected to the negative electrode of the capacitor 202 and the other end of the resistor 203. The capacitor 202, resistor 203 and diode 204 form a snubber circuit that absorbs the transient high voltage associated with switching.

The first terminal of the switching element 205 and the other end of the primary side of the transformer 220 are connected to the anode of the diode 204. The switching element 205 is connected in series with the primary winding of the transformer 220. The second terminal of the switching element 205 is connected to the negative electrode of the capacitor 201. The control terminal of the switching element 205 is connected to the control IC 200. The control terminal is a terminal for switching between the first and second terminals.

The switching element 205 is, for example, a MOSFET (Metal-Oxide-Semiconductor Field-Effective Transistor). When the switching element 205 is a MOSFET, the first terminal is a drain terminal, the second terminal is a source terminal, and the control terminal is a gate terminal. In the switching element 205, the first terminal is connected to the transformer 220, the second terminal is connected to the grounding terminal, and the control terminal is connected to the control IC 200.

The control IC 200 is, for example, a PFC (Power Factor Direction) driver. The control IC 200 drives the switching element 205. The anode of the diode 208 is connected to the auxiliary winding on the primary side of the transformer 220. The cathode of the diode 208 is connected to the power supply terminal of the control IC 200. The diode 208 supplies power to the control IC 200 from the auxiliary winding of the transformer 220.

A photocoupler 207 is connected to the control IC 200. The photocoupler 207 is provided to input information on the secondary side of the transformer 220 to the control IC 200.

The regular power supply circuit 2 includes an input voltage detection circuit 211. The input voltage detection circuit 211 detects the input voltage to the regular power supply circuit 2. The detected input voltage is input to the control unit 50 via the photocoupler 212. As a result, the control unit 50 detects the input voltage of the regular power supply circuit 2.

The anode of the diode 209 is connected to one end of the flyback winding on the secondary side of the transformer 220. The diode 209 is connected in series with the secondary side of the transformer 220 and is provided to transmit a stable voltage to the output side. The positive electrode of the electrolytic capacitor 214 is connected to the cathode of the diode 209. The negative electrode of the electrolytic capacitor 214 is connected to the grounding terminal.

In the grounding line of the regular power supply circuit 2, the primary side and the secondary side of the transformer 220 are insulated by a capacitor 213.

The regular power supply circuit 2 includes an output voltage detection circuit. The output voltage detection circuit is composed of a resistor 215 and a resistor 216 connected in series. The output voltage detection circuit is connected in parallel with the electrolytic capacitor 214. The voltage dividing values of the resistors 215 and 216 are input to the control unit 50. As a result, the control unit 50 detects the output voltage Vout of the regular power supply circuit 2.

The control unit 50 calculates a target value according to the output voltage Vout of the regular power supply circuit 2. After that, the control unit 50 outputs a voltage corresponding to the target value from the output terminal. This voltage is transmitted to the primary side via the photocoupler 207. The primary side of the photocoupler 207 is connected to the control IC 200. The control IC 200 receives the target value from the control unit 50 via the photocoupler 207. The control IC 200 controls the on / off of the switching element 205 so that the target value and the output voltage Vout of the regular power supply circuit 2 match. As a result, constant voltage feedback of the regular power supply circuit 2 which is an insulated flyback circuit is realized.

The charging circuit 3 charges the battery 250. The charging circuit 3 is connected to the forward winding on the secondary side of the transformer 220. The anode of the diode 31 is connected to the forward winding output on the secondary side of the transformer 220. An electrolytic capacitor 32 is connected between the cathode of the diode 31 and the grounding terminal. The diode 31 and the electrolytic capacitor 32 are provided to transmit a stable voltage to the charging circuit 3.

The first terminal of the switching element 33 is connected to the cathode of the diode 31 and the positive electrode of the electrolytic capacitor 32. One end of the resistor 34 is connected to the second terminal of the switching element 33. The positive electrode of the battery 250 is connected to the other end of the resistor 34. The resistor 34 is connected in series with the battery 250. The negative electrode of the battery 250 is connected to the grounding terminal. That is, the switching element 33, the resistor 34, and the battery 250 are connected in series to the output end of the regular power supply circuit 2.

The switching element 33 is, for example, a transistor. When the switching element 33 is a transistor, the first terminal is a collector, the second terminal is an emitter, and the control terminal is a base. The control terminal is a terminal for switching between the first and second terminals.

The positive electrode of the capacitor 98 and one end of the resistor 97 are connected to the control terminal of the switching element 33. The negative electrode of the capacitor 98 is connected to the grounding terminal. The other end of the resistor 97 is connected to one end of the resistor 99 and the first terminal of the transistor 77a. The other end of the resistor 99 is connected to the cathode of the diode 31 and the positive electrode of the electrolytic capacitor 32.

The second terminal of the transistor 77a is connected to a grounding terminal. The control terminal of the transistor 77a is connected to the control unit 50. The second terminal of the transistor 77a and the control terminal are connected by a resistor 77c. In this way, the control terminal of the switching element 33 is connected to the control unit 50 via the resistor 97, the transistor 77a, and the resistor 77b. The control unit 50 controls the on / off of the switching element 33.

One end of the series circuit of the resistors 35 and 36 is connected to the connection point between the second terminal of the switching element 33 and the resistor 34. The other end of the series circuit of the resistors 35 and 36 is connected to the grounding terminal. The connection points of the resistors 35 and 36 are connected to the control unit 50. The resistors 35 and 36 are provided so that the control unit 50 can detect the voltage across the series circuit of the resistor 34 and the battery 250.

The control unit 50 detects the voltage across the resistor 34. The control unit 50 turns on / off the switching element 33 so that the voltage across the resistor 34 matches the target value. As a result, the impedance of the switching element 33 is changed, and the battery 250 is charged with a constant current. That is, the charging current of the battery 250 is feedback-controlled with a constant current. The battery 250 is supplied with a charging current from the output voltage Vout of the regular power supply circuit 2.

In the lighting circuit 4, the switching element 42 and the resistor 43 are connected in series with the light source unit 41. Similarly, the switching element 47 and the resistor 48 are connected in series with the light source unit 46. The switching elements 42 and 47 are, for example, MOSFETs. The first terminals of the switching elements 42 and 47 are connected to the light source units 41 and 46, respectively. Further, the second terminals of the switching elements 42 and 47 are connected to one ends of the resistors 43 and 48, respectively. The control terminals of the switching elements 42 and 47 are connected to the control unit 50, respectively. The other ends of the resistors 43 and 48 are connected to the grounding terminal. A signal is output from the control unit 50 so that the switching elements 42 and 47 operate in the active region. The control unit 50 turns the switching elements 42 and 47 on and off to control the light source current flowing through the light source units 41 and 46.

A series circuit of resistors 44a and 44b is connected between the first terminal of the switching element 42 and the grounding terminal. The connection points of the resistors 44a and 44b are connected to the control unit 50. A series circuit of resistors 49a and 49b is connected between the first terminal of the switching element 47 and the grounding terminal. The connection points of the resistors 49a and 49b are connected to the control unit 50. With the resistors 44a and 44b and the resistors 49a and 49b, the voltage of the first terminal of the switching elements 42 and 47 can be detected by the control unit 50.

One ends of the resistors 43 and 48 are connected to the control unit 50, respectively. Therefore, the voltages across the resistors 43 and 48 are detected by the control unit 50, respectively. The control unit 50 turns the switching elements 42 and 47 on and off so that the voltage applied to the resistors 43 and 48 matches a predetermined value. The control unit 50 feedback-controls the switching elements 42 and 47. As a result, the impedances of the switching elements 42 and 47 are changed, and the light source units 41 and 46 can be controlled with a constant current, respectively. That is, the control unit 50 turns on / off the switching elements 42 and 47 so that the light source current matches a predetermined value.

The emergency lighting circuit 5 is composed of a step-up switching circuit. The emergency lighting circuit 5 is supplied with electric power from the battery 250 in an emergency such as a power failure of the external power supply AC or a pseudo power failure, boosts the output voltage of the battery 250, and lights the light source units 41 and 46.

A capacitor 51 is connected in parallel to the input end of the emergency lighting circuit 5. The positive electrode of the battery 250 and one end of the coil 52 are connected to the positive electrode of the capacitor 51. The negative electrode of the capacitor 51 is connected to the grounding terminal. The other end of the coil 52 is connected to the anode of the diode 54. The cathode of the diode 54 is connected to the positive electrode of the capacitor 55. The negative electrode of the capacitor 55 is connected to the negative electrode of the capacitor 51. That is, a series circuit in which the coil 52, the diode 54, and the capacitor 55 are connected in this order is connected in parallel with the capacitor 51. Further, the anode side of the light source units 41 and 46 is connected to the positive electrode of the capacitor 55.

A switching element 53 is connected between the connection point of the coil 52 and the diode 54 and the grounding terminal. The first terminal of the switching element 53 is connected to the anode of the diode 54. The second terminal of the switching element 53 is connected to the negative electrode of the capacitor 51. The control terminal of the switching element 53 is connected to the control unit 50. The switching element 53 is, for example, a MOSFET.

The output voltage detection circuit described above is connected in parallel with the capacitor 55. The voltage dividing values of the resistors 215 and 216 are input to the control unit 50. As a result, the control unit 50 detects the output voltage of the emergency lighting circuit 5. The control unit 50 turns on / off the switching element 53 so that the detection voltage of the voltage detection circuit matches the target value. That is, the control unit 50 feedback-controls the emergency lighting circuit 5. As a result, constant voltage control of the emergency lighting circuit 5 is realized.

The power generation circuit 6 generates the power supply for the control unit 50. The power generation circuit 6 includes a diode 61, regulators 62, 63, and a reset circuit 64. The anode of the diode 61 is connected to the positive electrode of the electrolytic capacitor 214. The output voltage Vout of the regular power supply circuit 2 is applied to the electrolytic capacitor 214. A regulator 62 is connected between the cathode of the diode 61 and the grounding terminal.

Further, the positive electrode of the capacitor 55 is connected to the input of the regulator 62. The output voltage of the emergency lighting circuit 5 is applied to the capacitor 55.

The regulator 62 is provided to stabilize the voltage. The voltage Vcc2 is generated by the regulator 62. This voltage is supplied to the control unit 50. Since the normal power supply circuit 2 is operating during normal use, the regulator 62 generates a power supply from the output voltage Vout of the normal power supply circuit 2 via the diode 61. That is, the control unit 50 is supplied with power from the output voltage Vout of the regular power supply circuit 2. Since the emergency lighting circuit 5 is operating in an emergency, the regulator 62 generates a power supply from the output voltage of the emergency lighting circuit 5.

The power generation circuit 6 may further include a regulator 63 that generates a voltage Vcc1. The voltage Vcc1 is supplied as a power source to, for example, an infrared sensor 74 described later.

The control circuit 7 includes switches 71 and 72 for pseudo power failure and a reset switch 73 for resetting life information and the like. Further, the control circuit 7 includes an infrared sensor 74 for receiving the remote controller and an LED 75 for displaying. The switches 71 and 72, the reset switch 73, the infrared sensor 74, and the display LED 75 are connected to the control unit 50. Signals from the switches 71 and 72, the reset switch 73, the infrared sensor 74, and the display LED 75 are input to the control unit 50, respectively. By processing these signals in the control unit 50, a pseudo power failure state can be generated. Therefore, it is possible to confirm whether or not the emergency lighting device 100 can operate normally when the external power supply AC has a power failure.

The control unit 50 includes a CPU that performs various calculations, a memory, and a timer. A table used for CPU calculation is written in the memory in advance. The memory is composed of, for example, a non-volatile memory.

FIG. 2 is a circuit block diagram of the lighting circuit 4 according to the first embodiment. The lighting circuit 4 includes a plurality of series circuits 40 and 45. The series circuit 40 has a light source connecting portion 40a for connecting the light source unit 41, a switching element 42 connected in series with the light source connecting portion 40a, and a resistor 43 connected in series with the switching element 42. The resistor 43 is a current detection unit. The output voltage Vout of the regular power supply circuit 2 is supplied to both ends of the series circuit 40.

Similarly, the series circuit 45 has a light source connection unit 45a for connecting the light source unit 46, a switching element 47 connected in series with the light source connection unit 45a, and a resistor 48 connected in series with the switching element 47. .. The resistor 48 is a current detection unit. The output voltage Vout of the regular power supply circuit 2 is supplied to both ends of the series circuit 45.

In this embodiment, two series circuits 40 and 45 are provided. The number of series circuits included in the lighting circuit 4 may be one or more.

The light source unit 41 has LEDs 41a and 41b connected in series. The light source unit 46 has LEDs 46a and 46b connected in series. The number of LEDs provided in each of the light source units 41 and 46 may be one or more.

The resistors 44a and 44b form the voltage detection unit 44. The voltage detection unit 44 detects the voltage applied to both ends of the series circuit formed by the switching element 42 and the resistor 43. As a result, the control unit 50 can detect the voltage applied to the switching element 42. Similarly, the resistors 49a and 49b constitute the voltage detection unit 49. The voltage detection unit 49 detects the voltage applied to both ends of the series circuit formed by the switching element 47 and the resistor 48. As a result, the control unit 50 can detect the voltage applied to the switching element 47.

Next, a method of adjusting the output voltage Vout will be described. In order to light the LEDs, it is necessary to apply a voltage equal to or higher than the forward voltage VF to each LED. In FIG. 2, the forward voltage of the light source units 41 and 46 is shown as VF, and the forward voltage of each LED is shown as VF_s. In the present embodiment, when the output voltage Vout of the regular power supply circuit 2 is applied to the lighting circuit 4, a current starts to flow in the light source units 41 and 46. As a result, the light source units 41 and 46 are turned on.

The voltages across the resistors 43 and 48 are input to the control unit 50, respectively. The control unit 50 operates the voltage of the control terminals of the switching elements 42 and 47 so that the voltage across the resistors 43 and 48 becomes the preset target voltage Vref1. As a result, the impedance of the switching elements 42 and 47 changes, and a constant current flows through the light source units 41 and 46. A current determined by the resistance value of the target voltage Vref1 ÷ resistance 43 flows through the series circuit 40. A current determined by the resistance value of the target voltage Vref1 ÷ resistance 48 flows through the series circuit 45.

The voltage Vd across the switching element 42 and the resistor 43 is input to the control unit 50 as a voltage dividing voltage of the resistors 44a and 44b. The control unit 50 adjusts the output voltage Vout of the regular power supply circuit 2 so that the divided voltage of the resistors 44a and 44b becomes the target voltage Vref2. Specifically, the control unit 50 controls the on / off of the switching element 205 to adjust the output voltage Vout. When the voltage dividing voltage of the resistors 44a and 44b is larger than the target voltage Vref2, the control unit 50 lowers the output voltage Vout of the regular power supply circuit 2. The control unit 50 may adjust the output voltage Vout of the regular power supply circuit 2 so that the divided voltage of the resistors 49a and 49b becomes the target voltage Vref2.

That is, the control unit 50 sets the output voltage Vout to a fixed value so that the voltage across the switching element 42 matches the predetermined first voltage according to the detection voltage of the voltage detection unit 44. The fixed value is the value of the output voltage Vout when the voltage across the switching element 42 becomes the first voltage. Similarly, the control unit 50 may set the output voltage Vout to a fixed value so that the voltage across the switching element 47 matches the first voltage according to the detection voltage of the voltage detection unit 49.

The control unit 50 sets the output voltage Vout to a fixed value so that the voltage across the switching element 42 or the switching element 47 matches the first voltage, and then sets the output voltage Vout regardless of the voltage across the switching elements 42 and 47. Keep at a fixed value. The control unit 50 stores a fixed value. After that, the control unit 50 controls the output voltage Vout so that the output voltage Vout always becomes a stored fixed value.

Guide lights are generally provided to guide people in the area to safely evacuate in the event of a fire, earthquake, other disaster, or power outage in the event of an accident in a place where an unspecified number of people gather. .. In the emergency lighting device 100, the battery 250 is charged by the electric power from the external power supply AC during normal use, and the light source is turned on by the electric power from the battery 250 in an emergency such as when the external power supply AC has a power failure. In the present embodiment, the output voltage Vout of the regular power supply circuit 2 is always maintained at a fixed value. Therefore, a sufficient charging current can be obtained from the output voltage Vout. In addition, the power supply for the control unit 50 can be reliably secured.

Further, the forward voltage VF of the LED may vary. The forward voltage VF also changes depending on the current value or temperature flowing through the LED. Therefore, in general, the output voltage of the normal power supply circuit and the emergency lighting circuit needs to be set by assuming a forward voltage VF in consideration of the variation in the characteristics of each LED, the current, and the temperature.

On the other hand, in the present embodiment, the value of the output voltage Vout is set to a fixed value so that the voltage across the switching element 42 or the switching element 47 becomes the first voltage which is the target value. That is, even if the forward voltage VFs of the light source units 41 and 46 vary, the output voltage Vout of the regular power supply circuit 2 can be adjusted so that a voltage suitable for the switching elements 42 and 47 is applied. Therefore, it is possible to suppress an increase in the drain-source voltage of the switching elements 42 and 47. Therefore, the loss of the switching elements 42 and 47 can be suppressed, and the energy consumption can be suppressed.

Further, in the present embodiment, the light source current flowing through the light source units 41 and 46 is controlled to be constant. That is, even if the output voltage Vout of the regular power supply circuit 2 is set low, the light source current flowing through the light source units 41 and 46 is kept constant. Therefore, the light source units 41 and 46 can be driven stably. In addition, the input power from the external power supply AC can be reduced. Therefore, energy consumption can be suppressed.

Further, once the output voltage Vout of the regular power supply circuit 2 is set, it is fixed at a fixed value. After the output voltage Vout is fixed to a fixed value, it does not change even if the voltage across the switching elements 42 and 47 or the light source current fluctuates. Therefore, after the output voltage Vout is fixed, it is not necessary to control the light source current with a constant current while controlling the output voltage Vout with a constant voltage. Therefore, the control by the control unit 50 can be simplified and facilitated. Therefore, the control unit 50 can be operated with low power consumption.

Further, in the emergency lighting device 100, the light source units 41 and 46 are generally lit with a constant brightness during normal use. In this case, the light source current is kept constant after lighting. Since the light source current does not fluctuate, the voltage across the switching elements 42 and 47 is constant even if the output voltage Vout is kept constant. Therefore, even if the output voltage Vout is kept constant, it is possible to prevent an excessively large voltage from being applied to the switching elements 42 and 47.

Further, when a short circuit failure occurs in the light source units 41 and 46, it is conceivable that the voltage across the switching elements 42 and 47 rises. In the present embodiment, the control unit 50 maintains the output voltage Vout at a fixed value before and after a short circuit occurs in the light source units 41 and 46. Therefore, it is possible to prevent the output voltage Vout from decreasing as the voltage across the switching elements 42 and 47 increases. Therefore, it is possible to secure the required charging current from the output voltage Vout and obtain a constant voltage such as Vcc1 and Vcc2.

Further, the control unit 50 may set the output voltage Vout to a fixed value so that the voltage across the switching element 42 or the switching element 47 matches the first voltage when the light source units 41 and 46 are turned on. The control unit 50 may set the output voltage Vout to a fixed value after a predetermined time, for example, after the light source units 41 and 46 start lighting. The specified time is, for example, the time required for the light source current to stabilize.

Further, the control unit 50 may set the output voltage Vout to a fixed value so that the voltage across the switching element having the smallest voltage across the switching elements 42 and 47 matches the first voltage. After setting the output voltage Vout to a fixed value, the control unit 50 maintains the output voltage Vout at a fixed value regardless of the voltage across the plurality of switching elements 42 and 47. As a result, a voltage equal to or higher than a specified value can be applied to each switching element.

Further, the control unit 50 may set the output voltage Vout to a fixed value so that the average value of the voltages across the plurality of switching elements 42 and 47 matches the first voltage. After setting the output voltage Vout to a fixed value, the control unit 50 maintains the output voltage Vout at a fixed value regardless of the voltage across the plurality of switching elements 42 and 47.

Further, the lighting device of the present embodiment is not limited to the emergency lighting device 100, and can be applied to any lighting device.

These modifications can be appropriately applied to the lighting device and the lighting device according to the following embodiments. Since the lighting device and the lighting device according to the following embodiments have much in common with the first embodiment, the differences from the first embodiment will be mainly described.

Embodiment 2.
FIG. 3 is a diagram illustrating a short-circuit waveform according to the second embodiment. The operation when the LED is short-circuited during lighting in the emergency lighting device 100 will be described. Hereinafter, the operation will be described using the series circuit 40, but the operation of the series circuit 45 is also the same. When a lighting signal is input to the control unit 50 from the outside, the output voltage Vout rises. Along with this, the voltage across the switching element 42 and the light source current increase.

The light source current stabilizes at the target value after a lapse of a specified time after the input of the lighting signal. At this time, the output voltage Vout becomes a normal value, and the voltage across the switching element 42 becomes the first voltage. The control unit 50 determines a fixed value of the output voltage Vout after a specified time from the input of the lighting signal or after a specified time after the light source current matches the target value. After that, the control unit 50 maintains the output voltage Vout at a fixed value.

In FIG. 3, the behavior of the output voltage Vout for the three types of forward voltage VF is shown by solid lines 81 to 83. The solid line 81 shows the output voltage Vout when the forward voltage VF of the light source unit 41 is smaller than that of the solid line 82. The solid line 82 shows the output voltage Vout when the forward voltage VF of the light source unit 41 is smaller than that of the solid line 83. The larger the forward voltage VF, the larger the output voltage Vout.

If the light source unit 41 is short-circuited during lighting, the forward voltage VF of the light source unit 41 decreases. Therefore, the voltage across the switching element 42 rises. Next, the control unit 50 detects that the voltage across the switching element 42 is larger than the predetermined second voltage. The second voltage is larger than the first voltage. As a result, the control unit 50 detects a short-circuit failure and enters a protected state. The voltage larger than the second voltage is the voltage generated by the short circuit of the light source unit 41.

When a voltage larger than the second voltage is applied to the switching element 42, the control unit 50 stops the light source current flowing through the light source unit 41.

Further, even after the light source unit 41 is short-circuited, the control unit 50 maintains the output voltage Vout at a fixed value. Therefore, in the protected state, the voltage across the switching element 42 is maintained at the second voltage or higher.

In FIG. 3, the behavior of the voltage across the switching element 42 for the three types of forward voltage VF is shown by solid lines 84 to 86. The voltages across the switching elements 42 shown by the solid lines 84 to 86 correspond to the output voltages Vout shown by the solid lines 81 to 83, respectively. After the protection state is reached, the forward voltage VF of the light source unit 41 decreases due to the decrease in the light source current. Therefore, the voltage across the switching element 42 rises above the second voltage.

FIG. 4 is a diagram illustrating a short-circuit waveform according to a comparative example. First, as a first comparative example, a case where the output voltage Vout is always controlled so that the voltage across the switching element 42 matches the first voltage, but the light source current is not stopped even if a short circuit is detected will be described. In FIG. 4, the short-circuit waveform of the first comparative example is shown by a solid line. In the first comparative example, if the light source unit 41 is short-circuited during lighting, the forward voltage VF of the light source unit 41 decreases. Therefore, the feedback of the output voltage Vout cannot catch up, and the voltage across the switching element 42 rises.

Next, the control unit 50 detects that the voltage across the switching element 42 is higher than the first voltage. The control unit 50 lowers the output voltage Vout of the regular power supply circuit 2 so that the voltage across the switching element 42 becomes the first voltage. As a result, the output voltage Vout is lower than the normal value.

As described above, in the first comparative example, the output voltage Vout fluctuates. Therefore, it may be difficult to secure the required charging current from the output voltage Vout and to obtain a constant voltage such as Vcc1 or Vcc2. In FIG. 4, the required voltage, which is the output voltage Vout required for securing the charging current and securing the power supply for the control unit 50, is shown by a broken line.

Next, as a second comparative example, a case where the lower limit value of the output voltage Vout is set will be described. In FIG. 4, the short-circuit waveform of the second comparative example is shown by the dotted line. In this case, the control unit 50 maintains the output voltage Vout at or above the lower limit. In the example of FIG. 4, the lower limit value of the output voltage Vout is set to a normal value which is a value of the output voltage Vout in the normal state. As a result, the output voltage Vout does not drop below the normal value. Therefore, it is possible to secure a necessary charging current from the output voltage Vout and obtain a constant voltage such as Vcc1 and Vcc2.

However, an extra voltage Va will continue to be applied to the switching element 42. The voltage Va is the difference between the voltage across the switching element 42 and the first voltage. At this time, a useless loss occurs in the switching element 42. The loss is voltage Va × light source current IF, where IF is the light source current of the light source unit 41. As described above, in the second comparative example, when the light source unit 41 has a short-circuit failure, the voltage share of the switching element 42 increases. Therefore, the heat generation of the switching element 42 may increase.

On the other hand, in the present embodiment, an extra voltage is applied to both ends of the switching element 42 in the protected state, while the current of the light source unit 41 is stopped. Therefore, even if an extra voltage is applied to the switching element 42, no useless loss occurs in the switching element 42. Therefore, the heat generation of the switching element 42 can be suppressed, and the energy consumption of the emergency lighting device 100 can be reduced. Further, since the heat radiation plate and the like can be reduced by suppressing heat generation, the emergency lighting device 100 can be manufactured at low cost.

Further, the output voltage Vout is maintained at a fixed value even in the protected state. Therefore, it is possible to secure a necessary charging current from the output voltage Vout and obtain a constant voltage such as Vcc1 and Vcc2.

Further, the display LED 75 is equipped with a lamp monitor that notifies an abnormality of the light source units 41 and 46. When the control unit 50 detects a short-circuit failure, the lamp monitor of the display LED 75 may be turned on. As a result, the user can be prompted to replace the light source units 41 and 46.

As a modification of this embodiment, the control unit 50 may reduce the light source current of the light source unit 41 when a voltage larger than the second voltage is applied to the switching element 42. In this case as well, wasteful loss and heat generation of the switching element 42 can be suppressed.

Further, when a voltage larger than the second voltage is applied to the switching element in any one of the plurality of series circuits 40 and 45, the control unit 50 lowers the light source current in each of the plurality of series circuits 40 and 45. You may let me. That is, when the maximum value of the voltages across the switching elements 42 and 47 exceeds the second voltage, the control unit 50 may reduce the light source currents of the light source units 41 and 46, respectively.

Further, the control unit 50 may reduce the light source current in each of the plurality of series circuits 40 and 45 when the average value of the voltages applied to the switching elements 42 and 47 becomes larger than the second voltage.

The technical features described in each embodiment may be used in combination as appropriate.

1 Input filter circuit, 2 Regular power supply circuit, 3 Charging circuit, 4 Lighting circuit, 5 Emergency lighting circuit, 6 Power supply generation circuit, 7 Control circuit, 10 units, 11 Fuse, 12 Capacitor, 13 Diode bridge, 14 Off signal detection circuit , 15 photocoupler, 31 diode, 32 electrolytic capacitor, 33 switching element, 34 resistance, 35 resistance, 40 series circuit, 40a light source connection part, 41 light source part, 42 switching element, 43 resistance, 44 voltage detector, 44a resistance, 45 series circuit, 45a light source connection part, 46 light source part, 47 switching element, 48 resistance, 49 voltage detection part, 49a resistance, 50 control part, 51 capacitor, 52 coil, 53 switching element, 54 capacitor, 55 capacitor, 61 diode , 62 regulator, 63 regulator, 64 reset circuit, 71 switch, 73 reset switch, 74 infrared sensor, 77a transistor, 77b resistance, 77c resistance, 97 resistance, 98 capacitor, 99 resistance, 100 emergency lighting device, 200 control IC, 201 capacitor, 202 capacitor, 203 capacitor, 204 capacitor, 205 switching element, 207 photocoupler, 208 diode, 209 diode, 211 input voltage detection circuit, 212 photocoupler, 213 capacitor, 214 electrolytic capacitor, 215 resistor, 216 resistor, 220 Capacitor, 250 battery, AC external power supply, IF light source current, LED75 display, SW switch

Claims (13)

Power supply circuit and
A series circuit having a light source connection portion for connecting a light source and a switching element connected in series with the light source connection portion, and supplying the output voltage of the power supply circuit to both ends.
A control unit that turns the switching element on and off to control the light source current flowing through the light source.
With
The control unit sets the output voltage to a fixed value so that the voltage across the switching element matches a predetermined first voltage, and then sets the output voltage to the output voltage regardless of the voltage across the switching element. A lighting device characterized by maintaining a fixed value. The lighting device according to claim 1, wherein the control unit maintains the output voltage at the fixed value before and after a short circuit occurs in the light source. The first or second aspect of the present invention, wherein the control unit sets the output voltage to the fixed value so that the voltage across the switching element matches the first voltage when the light source is turned on. Lighting device. The lighting device according to any one of claims 1 to 3, wherein the control unit turns the switching element on and off so that the light source current matches a predetermined value. The series circuit has a current detection unit connected in series with the switching element.
The lighting device according to claim 4, wherein the control unit turns the switching element on and off so that the voltage applied to the current detection unit matches a predetermined value. The series circuit has a current detection unit connected in series with the switching element.
The control unit sets the output voltage so that the voltage across the switching element matches the first voltage according to the voltage applied to both ends of the series circuit formed by the switching element and the current detection unit. The lighting device according to any one of claims 1 to 4, wherein the lighting device is set to the fixed value. Any of claims 1 to 6, wherein the control unit lowers the light source current when a voltage larger than the first voltage and larger than a predetermined second voltage is applied to the switching element. The lighting device according to item 1. The lighting device according to claim 7, wherein the control unit stops the light source current when a voltage larger than the second voltage is applied to the switching element. Power supply circuit and
With multiple series circuits,
Control unit and
With
Each of the plurality of series circuits has a light source connection portion for connecting a light source and a switching element connected in series with the light source connection portion, and an output voltage of the power supply circuit is supplied to both ends.
The control unit turns the switching element on and off for each of the plurality of series circuits to control the light source current flowing through the light source, and the switching element having the smallest voltage across the plurality of switching elements of the plurality of series circuits. After setting the output voltage to a fixed value so that the voltage across the two ends coincides with a predetermined first voltage, the output voltage is maintained at the fixed value regardless of the voltage across the plurality of switching elements. Lighting device. Power supply circuit and
With multiple series circuits,
Control unit and
With
Each of the plurality of series circuits has a light source connection portion for connecting a light source and a switching element connected in series with the light source connection portion, and an output voltage of the power supply circuit is supplied to both ends.
The control unit turns the switching element on and off for each of the plurality of series circuits to control the light source current flowing through the light source, and the average value of the voltages across the plurality of switching elements of the plurality of series circuits is predetermined. A lighting device characterized in that the output voltage is set to a fixed value so as to match the first voltage, and then the output voltage is maintained at the fixed value regardless of the voltage across the two. A battery to which a charging current is supplied from the output voltage of the power supply circuit and
An emergency lighting circuit that is supplied with power from the battery to light the light source in an emergency,
The lighting device according to any one of claims 1 to 10, wherein the lighting device comprises. The lighting device according to any one of claims 1 to 11, wherein the control unit is supplied with power from the output voltage of the power supply circuit. The lighting device according to any one of claims 1 to 12.
With the light source
A lighting device characterized by being provided with.

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